Summary of Significant Accounting Policies and Procedures and Newly Adopted Accounting Standards (Tables)

12 Months Ended

Dec. 31, 2020

Schedule of reconciliation of the denominator of the diluted net income per common share computation

The following is a reconciliation of the denominator of the basic net income per common share computation to the denominator of the diluted net income per common share computation.


	2020	2019	2018
Weighted average shares used for the basic net income per share computation	345,280,126	315,837,012	289,427,430
Incremental shares from share-based compensation	135,132	322,265	179,532
Weighted average partnership common units convertible to common shares that were dilutive	—	—	317,022
Weighted average shares used for diluted net income per share computation	345,415,258	316,159,277	289,923,984
Unvested shares from share-based compensation that were anti-dilutive	70,581	8,113	13,148
Weighted average partnership common units convertible to common shares that were anti-dilutive	463,119	442,073	297,576

Schedule of reserves recorded as reduction of rental revenue

The following table summarizes reserves recorded as a reduction of rental revenue (dollars in millions):


	Year ended December 31,
	2020		2019		2018
Rental revenue reserves	$	44.1	$	1.4	$	1.1
Straight-line rent reserves	8.4		1.5		0.2
Total rental revenue reserves	$	52.5	$	2.9	$	1.3

Schedule of estimated useful lives of assets

Properties are depreciated using the straight-line method over the estimated useful lives of the assets. The estimated useful lives are as follows:


Buildings			25 years or 35 years
Building improvements			4 to 35 years
Equipment			5 to 25 years
Lease commissions and property improvements to accommodate the client's use			The shorter of the term of the related lease or useful life
Acquired in-place leases			Remaining terms of the respective leases

Schedule of provisions for impairment

The following table summarizes our provisions for impairment during the periods indicated below (dollars in millions):


	Year Ended December 31,
	2020		2019		2018
Total provisions for impairment	$	147.2	$	40.2	$	26.3
Number of properties:
Classified as held for sale	6		1		—
Classified as held for investment	42		5		3
Sold	51		45		41